In the related art, there is known a poppet valve type fluid control valve that controls a flow rate of air supplied to various devices (e.g., a fuel cell or a three-way catalyst converter) mounted on a vehicle (see, e.g., JP 2013-087803A (Reference 1) and JP 2016-008683A (Reference 2)). The fluid control valve includes a shaft member that moves along an axis by a driving force of a driving source, a valve body connected to the tip end of the shaft member, and a housing that has an annular valve seat on which the valve body abuts and accommodates the shaft member and the valve body.
In the fluid control valve of Reference 1, the valve body is configured to be capable of swinging with respect to the shaft member, and a forward-direction driving force is applied to the shaft member such that the sealing member of the valve body is pressed against the valve seat over the entire circumference of the valve seat.
In the fluid control valve of Reference 2, a first protruding portion and a second protruding portion are formed in the sealing member provided in the valve seat. The first protruding portion protrudes toward the valve body, and the second protruding portion has a larger protrusion amount than that of the first protruding portion. The fluid control valve of Reference 2 has a double sealing structure in which, when the valve body is closed, the second protruding portion abuts on the valve body to be elastically deformed so that foreign matters such as water droplets attached to the valve body are scraped off, and subsequently, the first protruding portion comes into contact with the valve body.
However, in the poppet valve type fluid control valve, when the valve body is closed, the parallelism between the valve body and the valve seat may not be constant due to a fluid pressure received by the valve body from the fluid or a dimensional error of components. As a result, a problem occurs in that a gap is formed between the valve body and the valve seat, and thus, the sealing function is deteriorated.
In the fluid control valve of Reference 1, since the valve body swings with respect to the shaft member such that the sealing member of the valve body is pressed against the valve seat over the entire circumference of the valve seat, the sealing performance is high. However, excessive pressing stress may be applied to the sealing member, and thus, the durability of the sealing member may be impaired.
Further, in the fluid control valve of Reference 2, the sealing performance is improved by the double sealing structure. However, when the valve body is pressed against the valve seat by moving the shaft member, excessive pressing stress may be applied to the sealing member, and thus, the durability of the sealing member may be impaired.
Thus, a need exists for a fluid control valve which is not susceptible to the drawback mentioned above.